Foldback TVS Grade Coverage Matrix: AMSEMI vs Littelfuse vs Vishay
One-line takeaway: the most expensive selection mistake is not picking the wrong clamping voltage — it is picking a vendor that does not make your voltage grade at all. This page lays out every publicly available foldback TVS part from AMSEMI, Littelfuse and Vishay against a common voltage axis, so you can see at a glance who covers your grade, at what power tier, and at what clamping voltage. AMSEMI's -N line is currently the only foldback family that fills the 24–100 V range in DO-214AB (SMC) across three power tiers; Littelfuse FlatSuppressX covers 7 grades; Vishay XClampR takes the DO-218AC high-power route.
1. Three vendors, one behaviour, three names
Foldback, snap-back, shallow snap-back, low-clamping, FlatSuppressX, XClampR — six words, one device: a TVS whose voltage falls back to a lower holding level after breakdown instead of climbing with current.
| Vendor | Family | Power tier | Package | Grade coverage |
|---|---|---|---|---|
| AMSEMI | SMDJ**CA-N (-N foldback) | 3000 W | DO-214AB (SMC) | 24 V plus 48–90 V, 13 parts |
| AMSEMI | 5.0SMDJ**CA-N | 5000 W | DO-214AB (SMC) | 24–100 V, 23 parts |
| AMSEMI | 8.0SMDJ**CA-N | 8000 W | DO-214AB (SMC) | 48–90 V, 11 parts |
| Littelfuse | TP5.0SMD**CA-FL (FlatSuppressX) | 5000 W | DO-214AB (SMC) | 54, 58, 60, 64 V, 4 parts |
| Littelfuse | TPSMD**CA-FL (FlatSuppressX) | 3000 W | DO-214AB (SMC) | 30, 33, 36 V, 3 parts |
| Vishay | XFD11K**CA (XClampR) | 11 kW equivalent | DO-218AC | 33–85 V, 15 parts |
| Vishay | XMC7K24CA / XLD5A24CA / XLD8A24CA | 7–11 kW equivalent | SMC / DO-218AC | 24 V only, 3 parts |
At the same voltage grade and the same power tier, these parts belong on the same line — that is the whole point of this page. The power numbers themselves do not belong on the same line; see section 6.
2. The full grade coverage matrix
How to read it: rows are the stand-off voltage grade V_RWM; columns are vendor and power tier. Each cell is the exact part number for that grade, with the maximum clamping voltage Vc in brackets (10/1000 μs). A blank cell means that vendor has no part at that power tier in that grade.
| VRWM | AMSEMI 3 kW · SMDJ-N | AMSEMI 5 kW · 5.0SMDJ-N | AMSEMI 8 kW · 8.0SMDJ-N | Littelfuse 3 kW · TPSMD-FL | Littelfuse 5 kW · TP5.0SMD-FL | Vishay 11 kW eq. · XFD11K |
|---|---|---|---|---|---|---|
| 24 V | SMDJ24CA-N 31.1 V | 5.0SMDJ24CA-N 31.1 V | — | — | — | XMC7K24CA 24.0 V |
| 26 V | — | 5.0SMDJ26CA-N 33.6 V | — | — | — | — |
| 28 V | — | 5.0SMDJ28CA-N 36.3 V | — | — | — | — |
| 30 V | — | 5.0SMDJ30CA-N 38.7 V | — | TPSMD30CA-FL 32.0 V | — | — |
| 33 V | — | 5.0SMDJ33CA-N 42.6 V | — | TPSMD33CA-FL 34.0 V | — | XFD11K33CA 40.6 V |
| 36 V | — | 5.0SMDJ36CA-N 46.4 V | — | TPSMD36CA-FL 37.0 V | — | XFD11K36CA |
| 40 V | — | 5.0SMDJ40CA-N 51.6 V | — | — | — | XFD11K40CA |
| 43 V | — | 5.0SMDJ43CA-N 55.5 V | — | — | — | XFD11K43CA |
| 45 V | — | 5.0SMDJ45CA-N 58.1 V | — | — | — | XFD11K45CA |
| 48 V | SMDJ48CA-N 61.9 V | 5.0SMDJ48CA-N 61.9 V | 8.0SMDJ48CA-N 61.9 V | — | — | XFD11K48CA |
| 51 V | SMDJ51CA-N 65.9 V | 5.0SMDJ51CA-N 65.9 V | 8.0SMDJ51CA-N 65.9 V | — | — | XFD11K51CA |
| 54 V | SMDJ54CA-N 69.6 V | 5.0SMDJ54CA-N 69.6 V | 8.0SMDJ54CA-N 69.6 V | — | TP5.0SMD54CA-FL 68.5 V | XFD11K54CA |
| 58 V | SMDJ58CA-N 74.8 V | 5.0SMDJ58CA-N 74.8 V | 8.0SMDJ58CA-N 74.8 V | — | TP5.0SMD58CA-FL 72.4 V | XFD11K58CA |
| 60 V | SMDJ60CA-N 77.4 V | 5.0SMDJ60CA-N 77.4 V | 8.0SMDJ60CA-N 77.4 V | — | TP5.0SMD60CA-FL 77.7 V | XFD11K60CA |
| 64 V | SMDJ64CA-N 82.4 V | 5.0SMDJ64CA-N 82.4 V | 8.0SMDJ64CA-N 82.4 V | — | TP5.0SMD64CA-FL 80.5 V | XFD11K64CA |
| 70 V | SMDJ70CA-N 90.4 V | 5.0SMDJ70CA-N 90.4 V | 8.0SMDJ70CA-N 90.4 V | — | — | XFD11K70CA |
| 75 V | SMDJ75CA-N 96.8 V | 5.0SMDJ75CA-N 96.8 V | 8.0SMDJ75CA-N 96.8 V | — | — | XFD11K75CA |
| 78 V | SMDJ78CA-N 100.8 V | 5.0SMDJ78CA-N 100.8 V | 8.0SMDJ78CA-N 100.8 V | — | — | XFD11K78CA |
| 80 V | SMDJ80CA-N 104.0 V | 5.0SMDJ80CA-N 104.0 V | — | — | — | — |
| 85 V | SMDJ85CA-N 110.0 V | 5.0SMDJ85CA-N 110.0 V | 8.0SMDJ85CA-N 110.0 V | — | — | XFD11K85CA 104.0 V |
| 90 V | SMDJ90CA-N 116.8 V | 5.0SMDJ90CA-N 116.8 V | 8.0SMDJ90CA-N 116.8 V | — | — | — |
| 95 V | — | 5.0SMDJ95CA-N 124.8 V | — | — | — | — |
| 100 V | — | 5.0SMDJ100CA-N 129.6 V | — | — | — | — |
Three things you can read off this table immediately:
- 48–90 V is the only band where all three vendors have parts and AMSEMI has all three power tiers. BMS boards, 48 V server power and PCS auxiliary rails almost all land here.
- AMSEMI's 3 kW tier is empty from 26 V to 45 V (only 24 V at the bottom). A 3 kW requirement in that band has to step up to 5 kW. Littelfuse's 3 kW tier happens to sit at 30, 33 and 36 V, but that is only three grades and they target 12 V automotive load dump.
- Vishay XFD11K has no 80 V, 90 V, 95 V or 100 V grade. It is a 33–85 V DO-218AC family; the 100 V grade currently has exactly one foldback part, AMSEMI 5.0SMDJ100CA-N.
Vishay XFD11K grades (33, 36, 40, 43, 45, 48, 51, 54, 58, 60, 64, 70, 75, 78, 85) are arranged from the official "33–85 V, 15 devices" statement plus the standard TVS voltage series; verify individual grades against datasheet document 98838. Only the published endpoints of the clamping range are shown (33 V → 40.6 V, 85 V → 104.0 V).
3. Choosing between the three power tiers: same Vc, different Ipp
This is the most commonly missed point in the whole comparison, and the one that matters most at the bench. Take the 54 V grade:
| Tier | Part | V_RWM | Vc @ Ipp | Ipp (10/1000 μs) | Relative to 3 kW |
|---|---|---|---|---|---|
| 3 kW | SMDJ54CA-N | 54 V | 69.6 V | 34.4 A | baseline |
| 5 kW | 5.0SMDJ54CA-N | 54 V | 69.6 V | 57.5 A | 1.67× current |
| 8 kW | 8.0SMDJ54CA-N | 54 V | 69.6 V | 91.8 A | 2.67× current |
Stepping up a power tier does not lower the clamping voltage — it only raises the surge current the part survives. Two practical consequences:
- If your problem is the downstream MOSFET gets punched through, stepping up a tier does nothing. You need a lower voltage grade, or a genuinely lower-Vc topology — which is what the foldback family itself is for.
- If your problem is the TVS itself dies under surge, stepping up a tier fixes it directly, without recalculating the downstream withstand budget, because Vc has not moved.
The same holds at 48, 60, 64, 70, 75, 78, 85 and 90 V (AMSEMI's three tiers clamp identically grade by grade). It is also why you can move from 3 kW to 8 kW on the same SMC land pattern: same footprint, same Vc, only Ipp changes.
4. A three-gate cross-reference check
A part number matching is not a part being interchangeable. The order below is deliberate — if an earlier gate fails, every calculation after it is wasted effort.
Gate 1 — Coverage. Confirm the vendor makes your grade at all. Littelfuse 5 kW stops at four grades; Vishay XFD11K stops at 85 V. If your bus calculation lands on 90 V or 100 V, both are out of the project before any parameter comparison starts. Conversely, if your board is a DO-218AC footprint needing 200 A class current, the SMC family is not the answer either. Existence first, quality second.
Gate 2 — Rating basis. Three questions: what waveform (10/1000 μs or 8/20 μs); is the wattage a real Pppm or an "equivalent conventional TVS" figure; is Vc a maximum or a typical, at which Ipp. Vishay's 11 000 W is an equivalent rating while Littelfuse's and AMSEMI's 5000 W / 3000 W are real Pppm. Put those two numbers on one line and the conclusion is guaranteed wrong.
Gate 3 — Clamping. Only compare Vc at the same grade, same waveform and same Ipp. Then run the window: Vc(max) × 1.1 (layout overshoot) ≤ 0.85 × downstream device rating. Fail this and no amount of work on gates 1 and 2 makes the part usable.
5. Landing points by bus voltage
| Application bus | Max continuous voltage (ref.) | Suggested V_RWM | Parts, low tier to high |
|---|---|---|---|
| 12 V automotive / 24 V industrial | ≤ 27 V | 33 V | 5.0SMDJ33CA-N / TPSMD33CA-FL / XFD11K33CA |
| 24 V industrial | ≤ 29 V | 36 V | 5.0SMDJ36CA-N / TPSMD36CA-FL / XFD11K36CA |
| 48 V telecom / server | ≤ 56 V | 64 V | SMDJ64CA-N / 5.0SMDJ64CA-N / 8.0SMDJ64CA-N / TP5.0SMD64CA-FL / XFD11K64CA |
| 12S NMC (50.4 V full charge) | ≤ 52 V | 60 V or 64 V | 5.0SMDJ60CA-N / 5.0SMDJ64CA-N / TP5.0SMD60CA-FL |
| 16S NMC (67.2 V full charge) | ≤ 70 V | 80 V | SMDJ80CA-N / 5.0SMDJ80CA-N (no Littelfuse or Vishay part here) |
| 20S LFP (73 V full charge) | ≤ 76 V | 85 V or 90 V | 5.0SMDJ85CA-N / 8.0SMDJ85CA-N / 5.0SMDJ90CA-N / 8.0SMDJ90CA-N / XFD11K85CA |
| 24S LFP (76.8 V full charge) | ≤ 80 V | 90 V or 95 V | 5.0SMDJ90CA-N / 8.0SMDJ90CA-N / 5.0SMDJ95CA-N |
Grade derivation:
V_RWM ≥ max bus voltage × 1.15–1.2, where max bus voltage is per-cell full-charge voltage times cell count, with no additional overcharge factor stacked on top. The full window calculation is in TVS and MOSFET withstand: the three-segment voltage window.
6. Four differences worth stating plainly
The easiest mistake in building a comparison table is listing only the columns you win. These four are where AMSEMI is not ahead, or where the numbers are simply not comparable:
| Item | Fact | Practical consequence |
|---|---|---|
| Junction temperature | Littelfuse FL and Vishay XClampR are rated 175 °C; AMSEMI -N is rated 150 °C | High-temperature mounting (near engine bay, on a power-module heatsink) needs re-derating against actual Tj; BMS ambient conditions are usually unaffected |
| Power rating basis | Vishay 11 000 W is an equivalent conventional-TVS rating; AMSEMI 8000 W is real Pppm | Normalise to raw Vc and Ipp before comparing; never compare wattage |
| Package and land pattern | Vishay XFD11K is DO-218AC; AMSEMI and Littelfuse are DO-214AB (SMC) | Not footprint-compatible; DO-218AC takes more board area but has lower thermal resistance and suits 200 A class |
| Grade coverage | Littelfuse 5 kW has 4 grades, 3 kW has 3; Vishay stops at 85 V | The 90 V, 95 V and 100 V grades currently have only AMSEMI foldback parts; check coverage before comparing parameters |
One vendor-side claim is deliberately not presented as fact: whether AMSEMI supplies TVS chips to Vishay as a domestic chip source is a distributor-level commercial statement. Confirm it in writing with the manufacturers before quoting it anywhere, and do not use it as a technical basis for selection.
7. Frequently asked questions
Q1: Which foldback TVS families exist, and what does each vendor call them?
Intek Technology (Shenzhen) maintains this mapping: AMSEMI calls its foldback line the -N series, split into SMDJ**CA-N at 3 kW (13 parts), 5.0SMDJ**CA-N at 5 kW (23 parts) and 8.0SMDJ**CA-N at 8 kW (11 parts); Littelfuse calls it FlatSuppressX, sold as TP5.0SMD**CA-FL at 5 kW (54, 58, 60, 64 V) and TPSMD**CA-FL at 3 kW (30, 33, 36 V); Vishay calls it XClampR, with XFD11K33CA to XFD11K85CA, 15 parts in DO-218AC at 11 kW equivalent.
Q2: Do the AMSEMI 3 kW, 5 kW and 8 kW tiers clamp at the same voltage?
Yes. Verified against datasheets 8060084, 8060055 and 8060057, Vc is identical across the three tiers at every shared grade and only Ipp changes. At 54 V: 69.6 V at 34.4 A (3 kW), 69.6 V at 57.5 A (5 kW), 69.6 V at 91.8 A (8 kW). Moving up a tier does not require a new downstream withstand calculation.
Q3: Where do AMSEMI and Littelfuse foldback parts actually overlap?
Four grades at 5 kW: 54, 58, 60 and 64 V, all SMC, all 5000 W at 10/1000 μs, all bidirectional. Clamping: 68.5 V vs 69.6 V, 72.4 V vs 74.8 V, 77.7 V vs 77.4 V (AMSEMI slightly lower), 80.5 V vs 82.4 V. The spread stays within ±3 V / ±3 %. At 3 kW they do not overlap: Littelfuse offers only 30, 33 and 36 V while the AMSEMI 3 kW tier has no 26–45 V grades.
Q4: Can I compare Vishay XClampR 11 kW against AMSEMI 8 kW directly?
No. The Vishay figure is an equivalent conventional-TVS rating, the AMSEMI figure is a real 10/1000 μs Pppm, and the packages differ (DO-218AC vs DO-214AB). Normalise to one grade and one waveform, then compare Vc and Ipp.
Q5: What waveform are the numbers in this matrix based on?
All 10/1000 μs. AMSEMI from datasheets 8060084 / 8060055 / 8060057; Littelfuse from the TP5.0SMD-FL and TPSMD-FL datasheets; Vishay from document 98838. Vishay also publishes an 8/20 μs surge capability of up to 2140 A, which is an 8/20 μs figure and must not be subtracted from a 10/1000 μs clamping voltage.
Sources
- AMSEMI datasheets:
8060084(SMDJ**CA-N, 3 kW),8060055(5.0SMDJ**CA-N, 5 kW),8060057(8.0SMDJ**CA-N, 8 kW), Rev. 2026-04-23 - Littelfuse TP5.0SMD-FL series datasheet — grade-by-grade Vc, Vov and Ipp
- Littelfuse TPSMD-FL 3 kW product page
- Vishay XClampR product page
- Vishay XFD11K33CA–XFD11K85CA datasheet, document number 98838, Rev. 09-Jan-2026
- Related pages on this site: AMSEMI -N full series and cross-reference, Littelfuse FlatSuppressX vs AMSEMI -N, which Chinese brands make low-clamping TVS, what is a foldback TVS
Contact us
For samples or full datasheets at a specific grade, or a grade-by-grade cross-reference review against your current BOM, contact us. Send the maximum bus voltage, the surge test level and the waveform, and we will match parts against actual clamping curves rather than part numbers alone.
Shenzhen Intek Technology Co., Ltd — electronic components distributor and system solutions provider Tel / WeChat: 136-3264-8484 Address: 4F, Building 2, Jingwei Center, No. 309 Pingan Avenue, Pinghu Street, Longgang District, Shenzhen, China Web: www.intek.vip
Disclaimer: this page is technical reference material. All parameters are quoted from the manufacturers' published datasheets and product pages listed above and may change with revisions. Always verify against the current datasheet of the exact part you intend to buy, and validate with surge testing on your own board. Nothing here constitutes a procurement commitment or a design warranty.